1、Designation: F 1717 04Standard Test Methods forSpinal Implant Constructs in a Vertebrectomy Model1This standard is issued under the fixed designation F 1717; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision
2、. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover the materials and methods forthe static and fatigue testing of spinal implant assemblies in avertebrectom
3、y model. The test materials for most combinationsof spinal implant components can be specific depending on theintended spinal location and intended method of application tothe spine.1.2 These test methods are intended to provide a basis forthe mechanical comparison among past, present, and futurespi
4、nal implant assemblies. They allow comparison of spinalimplant constructs with different intended spinal locations andmethods of application to the spine. These test methods are notintended to define levels of performance, since sufficientknowledge is not available to predict the consequences of the
5、use of a particular device.1.3 These test methods set out guidelines for load types andmethods of applying loads. Methods for three static load typesand one fatigue test are defined for the comparative evaluationof spinal implant assemblies.1.4 These test methods establish guidelines for measuringdi
6、splacements, determining the yield load, and evaluating thestiffness and strength of the spinal implant assembly.1.5 Some spinal constructs may not be testable in all testconfigurations.1.6 Values stated in SI units are to be regarded as standard.1.7 This standard does not purport to address all of
7、thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 638 Test Method for Ten
8、sile Properties of PlasticE 4 Practices for Force Verification of Testing MachinesE 6 Terminology Relating to Methods of Mechanical Test-ingE 739 Practice for Statistical Analysis of Linear or Linear-ized Stress-Life (S-N) and Strain-Life (e-N) Fatigue DataE 1150 Definitions of Terms Relating to Fat
9、igue3F 1582 Terminology Relating to Spinal ImplantsF 2077 Test Methods For Intervertebral Body Fusion De-vices3. Terminology3.1 Definitions:3.1.1 For definitions of terms relating to these test methods,see Terminology E 6, Terminology F 1582, and DefinitionsE 1150.3.2 Definitions of Terms Specific t
10、o This Standard:3.2.1 active length of the longitudinal elementthe straightline distance between the center of attachment of the superioranchor and the center of attachment of the inferior anchor.3.2.2 angular displacement at 2 % offset yield (degrees)the angular displacement of a construct measured
11、 via theactuator that produces a permanent angular displacement in theX-Y plane equal to 0.020 times the torsional aspect ratio (seePoint A in Fig. 1).3.2.3 block moment armthe perpendicular to the appliedload between the insertion point of an anchor and the axis ofthe hinge pin.3.2.4 compressive or
12、 tensile bending stiffness (N/mm)thecompressive or tensile bending yield force divided by elasticdisplacement (see the initial slope of line BC in Fig. 1).3.2.5 compressive or tensile bending ultimate load (N)themaximum compressive or tensile force in X-Z plane applied toa spinal implant assembly (s
13、ee the force at Point E in Fig. 1).The ultimate load should be a function of the device and not ofthe load cell or testing machine.3.2.6 compressive or tensile bending yield load (N)thecompressive or tensile bending force in X-Z plane necessary toproduce a permanent deformation equal to 0.020 times
14、theactive length of the longitudinal element (see the force at PointD in Fig. 1).3.2.7 coordinate system/axesthree orthogonal axes aredefined in Fig. 2 and Fig. 3. The anterior-posterior axis is Xwith positive being anterior. The medial-lateral axis is Y with1These test methods are under the jurisdi
15、ction of ASTM Committee F04 onMedical and Surgical Materials and Devices and are the direct responsibility ofSubcommittee F04.25 on Spinal Devices.Current edition approved Apr. 1, 2004. Published April 2004. Originallyapproved in 1996. Last previous edition approved in 2001 as F 1717 01.2For referen
16、ced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C
17、700, West Conshohocken, PA 19428-2959, United States.left being positive when viewed posteriorly. The superior-inferior axis is Z with superior being positive.3.2.8 displacement at 2 % offset yield (mm)the displace-ment of a construct measured via the actuator that produces apermanent deformation eq
18、ual to 0.020 times the active lengthof the longitudinal element (see Point A in Fig. 1).3.2.9 elastic angular displacement (degrees)the angulardisplacement at 2 % offset yield (see Point A in Fig. 1) minusthe 2 % offset angular displacement (see Point B in Fig. 1).(The distance between Point A and P
19、oint B in Fig. 1.)3.2.10 elastic displacement (mm)the displacement at 2 %offset yield (see Point A in Fig. 1) minus the 2 % offsetdisplacement (see Point B in Fig. 1). (The distance betweenPoint A and Point B in Fig. 1.)3.2.11 failurepermanent deformation resulting from frac-ture, plastic deformatio
20、n, or loosening beyond the ultimatedisplacement or loosening that renders the spinal implantassembly ineffective or unable to adequately resist load.3.2.12 fatigue lifethe number of loading cycles, N,ofaspecified character that the spinal implant assembly sustainsbefore failure of a specified nature
21、 occurs (see DefinitionsE 1150).3.2.13 insertion point of an anchorthe location where theanchor is attached to the test block. The insertion points shownin Figs. 2-15 are to be adhered to if possible. In situationswhere the design of the spinal implant assembly or themanufacturers surgical instructi
22、ons for installation dictateotherwise, the attachment points may deviate from thesedimensions.FIG. 1 Typical Load Displacement Curve or Torque AngulationCurveFIG. 2 A Standard Bilateral Construct Containing Screw, Rod andScrewFIG. 3 A Bilateral Hook, Rod, Screw, and Transverse ElementConstructF17170
23、423.2.14 intended method of applicationspinal implant as-semblies contain different types of anchors. Each type ofanchor has an intended method of application to the spine.3.2.15 intended spinal locationthe anatomic region of thespine intended for the application of the spinal implantassembly. Spina
24、l implant assemblies are developed for specificspinal locations such as the anterior cervical spine or theposterior thoracolumbar, lumbar, and lumbosacral spine.3.2.16 hinge pinthe cylindrical rod connecting a testblock to a side support. A cervical construct is secured with a9.6 mm diameter pin and
25、 the thoracolumbar, lumbar, andlumbosacral construct uses a 12.7 mm diameter pin.3.2.17 longitudinal directionthe initial spatial orientationparallel to the longitudinal element of the spinal implantassembly. The longitudinal direction is generally in thesuperior-inferior direction and therefore, ge
26、nerally parallel tothe z axis.3.2.18 maximum run out loadthe maximum load that canbe applied to a spinal implant assembly where all of the testedconstructs have withstood 5 000 000 cycles without a failure.3.2.19 permanent deformationthe displacement (mm) orangular displacement (degree) of the spina
27、l implant constructrelative to the initial unloaded condition as measured via theactuator after the applied load, moment, or torque has beenremoved.3.2.20 spinal implant assemblya complete spinal implantconfiguration as intended for surgical use. A spinal implantassembly will contain anchors, interc
28、onnections, and longitu-dinal elements and may contain transverse elements (see Fig. 4,Fig. 6, Fig. 8, Fig. 10, Fig. 12, and Fig. 14).3.2.21 spinal implant constructa complete spinal implantassembly attached to the appropriate test blocks.3.2.22 test blockthe component of the test apparatus formount
29、ing the spinal implant assembly. A specific design of testblock is required for each intended spinal location and intendedmethod of application. Fig. 5, Fig. 7, Fig. 9, Fig. 11, Fig. 13,and Fig. 15 describe the recommended designs for the testblocks; however, alternate designs can be used as long as
30、equivalent performance is demonstrated.3.2.23 test block load pointthe location on the test blockat which the resultant load is transmitted from the testapparatus.3.2.24 tightening torquethe specified torque that is ap-plied to the various threaded fasteners of the spinal implantassembly.3.2.25 tors
31、ional aspect ratiothe active length of thelongitudinal element divided by the distance from the center ofrotation to the insertion point of an anchor (for example: in Fig.2 1.70 for a 76-mm active length, X =40mmandY = 40/2mm).FIG. 4 Cervical Unilateral Construct Test Setup for Screws or BoltsF17170
32、43A 5LD5Lx21 y2!1/2(1)where:L = active length of longitudinal element,D = distance to insertion point,x = x distance to insertion point, andy = y distance to insertion point.3.2.26 torsional stiffness (N-m/degree)the yield torque(N-m) divided by elastic angular displacement (degrees) (theinitial slo
33、pe of line BC in Fig. 1).3.2.27 torsional ultimate load (N-m)the maximum torquein X-Yplane applied to a spinal implant assembly (the torque atPoint E in Fig. 1). The ultimate torque should be a function ofthe device and not of the load cell or testing machine.3.2.28 two percent (2 %) offset angular
34、displacement(degrees)a permanent angular displacement in the X-Y planemeasured via the actuator equal to 0.020 times the torsionalaspect ratio (for example: 1.95 for 1.70 3 0.02 3 180/pi)(see Point B in Fig. 1).3.2.29 two percent (2 %) offset displacement (mm)a per-manent deformation measured via th
35、e actuator equal to 0.020times the active length of the longitudinal element (for ex-ample: 1.52 mm for a 76 mm active length of the longitudinalelement or 0.70 mm for 35 mm) (see Point B in Fig. 1).3.2.30 ultimate displacement (mm)the displacement asso-ciated with the ultimate load, ultimate bendin
36、g load or ultimatetorque (the displacement at Point F in Fig. 1).FIG. 5 Cervical Unilateral UHWMPE Block for Screws or BoltsF17170443.2.31 yield torque (N-m)the torque in X-Y plane requiredto produce a permanent displacement of 0.020 times thetorsional aspect ratio (the torque at Point D in Fig. 1).
37、3.2.32 zero displacement intercept (mm)the intersectionof the straight line section of the load displacement curve andthe zero load axis (the zero displacement reference Point 0 inFig. 1).4. Summary of Test Methods4.1 Similar test methods are proposed for the mechanicalevaluation of cervical spinal
38、implant assemblies (see Fig. 4,Fig. 6, and Fig. 8) and thoracolumbar, lumbar, and lumbosacralspinal implant assemblies (see Fig. 10, Fig. 12, and Fig. 14).4.2 Testing of the spinal implant assemblies will simulate avertebrectomy model via a large gap between two Ultra HighMolecular Weight Polyethyle
39、ne (UHMWPE) test blocks. TheUHMWPE used to manufacture the test blocks should have atensile breaking strength equal to 40 6 3 MPa (see Specifica-tion D 638). The UHMWPE test blocks (see Fig. 5, Fig. 7, Fig.9, Fig. 11, Fig. 13, and Fig. 15) will eliminate the effects of thevariability of bone propert
40、ies and morphometry. Alternatedesigns of test blocks may be used as long as equivalentperformance is demonstrated.4.3 Three static mechanical tests and one dynamic test willevaluate the spinal implant assemblies. The three static me-chanical tests are compression bending, tensile bending, andtorsion
41、. The dynamic test is a compression bending fatigue.4.4 A specific clinical indication generally requires a spe-cific spinal implant assembly. Spinal implant assemblies willbe evaluated with test configurations which simulate theclinical requirements for the intended spinal location. Theintended spi
42、nal locations are both anterior (see Fig. 4) andposterior (see Fig. 6 and Fig. 8) surfaces of the cervical spineor both anterior (see Fig. 10) and posterior (see Fig. 12 and Fig.14) surfaces of the thoracolumbar, lumbar, and lumbosacralspine. The block moment arm (see 6.6) for a test configurationde
43、pends on the intended spinal location. The cervical spineconfiguration (see Fig. 5, Fig. 7, and Fig. 9) specifies one blockmoment arm, while a larger block moment arm (see Fig. 11,Fig. 13, and Fig. 15) is specified for the thoracolumbar, lumbar,and lumbosacral spine.4.5 The intended method of applic
44、ation of the spinal im-plant assembly may vary for specific anatomic regions andclinical indications. Spinal implant assemblies contain differenttypes of anchors. Each type of anchor has an intended methodof application to the spine. For example, one assembly mayinclude anterior vertebral body screw
45、s and rods (see Fig. 2),while another assembly may contain posterior sacral screws,hooks, rods, and transverse elements (see Fig. 3). The blockmoment arm of a test configuration will be independent of theintended method of application of a spinal implant assembly;therefore, the test data for differe
46、nt intended methods ofapplication may be compared.5. Significance and Use5.1 Spinal implants are generally composed of severalcomponents which, when connected together, form a spinalimplant assembly. Spinal implant assemblies are designed toFIG. 6 Cervical Bilateral Construct Test Setup for Screws o
47、r BoltsF1717045provide some stability to the spine while arthrodesis takesplace. These test methods outline standard materials andmethods for the evaluation of different spinal implant assem-blies so that comparison between different designs may befacilitated.5.2 These test methods are used to quant
48、ify the static anddynamic mechanical characteristics of different designs ofspinal implant assemblies. The mechanical tests are conductedin vitro using simplified load schemes and do not attempt tomimic the complex loads of the spine.5.3 The loads applied to the spinal implant assemblies invivo will
49、, in general, differ from the loading configurationsused in these test methods. The results obtained here cannot beused directly to predict in vivo performance. The results can beused to compare different component designs in terms of therelative mechanical parameters.5.4 Fatigue testing in a simulated body fluid or saline maycause fretting, corrosion, or lubricate the interconnections andthereby affect the relative performance of tested devices. Thistest should be initially performed dry (ambient room condi-tions) for consistency. The effect of
